A phase varying apparatus for an automobile engine has a camshaft, sprocket coaxial with the camshaft but operably coupled to the crankshaft of the engine, and a brake drum coaxial with the camshaft. To change valve timing of the engine, the apparatus is adapted to vary the relative phase angle between the camshaft and the sprockets by putting a brake on a brake drum by means of an electromagnetic clutch, thereby retarding in rotation the brake drum relative to the sprockets via a phase varying mechanism such as helical splines.
A Patent Document 1 cited below discloses an electromagnetic-brake mounting structure for use with a phase varying apparatus. This electromagnetic clutch (electromagnetic brake) is supported by an electromagnetic-clutch cover (engine casing), and get stopped relative to the electromagnetic-clutch cover by means of plural pins formed on the rear end of the clutch cover and inserted in the holes formed in the cover, as shown in FIG. 3.